(a) Technical Field
The present disclosure relates to a method and system for controlling charge and discharge of a battery. More particularly, the present disclosure relates to a method and system for controlling charge and discharge of a battery that increase battery charging power and enhance fuel efficiency by adjusting charging power of the battery associated with fuel efficiency of a hybrid vehicle and controlling the charging and discharging of the battery based on the adjusted charging power.
(b) Description of the Related Art
Hybrid vehicles operate through the use of power from an internal combustion engine and power from a battery. In particular, hybrid vehicles are designed to efficiently combine and use power of the internal combustion engine and the motor. For example, as illustrated in FIG. 1, a hybrid vehicle includes: an engine 10; a motor 20; an engine clutch 30 configured to control power connection between the engine 10 and the motor 20; a transmission 40; a differential gear unit 50; a battery 60; an integrated starter-generator (ISG) 70 configured to start the engine 10 or generate electric power by output of the engine 10; and a plurality of wheels 80. Although the integrated starter-generator 70 operates as a starter motor or a generator, since the integrated starter-generator 70 is associated with an engine start in the present disclosure, the integrated starter-generator 70 will be regarded as a starter motor in the description.
As further shown, the hybrid vehicle includes: a hybrid control unit (HCU) 200 configured to operate the hybrid vehicle; an engine control unit (ECU) 110 configured to operate the engine 10; a motor control unit (MCU) 120 configured to operate the motor 20; a transmission control unit (TCU) 140 configured to operate the transmission 40; and a battery control unit (BCU) 160 configured to manage and operate the battery 60. The BCU 160 may also be referred to as a battery management system (BMS). The ISG 70 may also be referred to as a starting and generating motor or a hybrid starter-generator (HSG).
The hybrid electric vehicle may be driven in a driving mode, such as an electric vehicle (EV) mode, which is a mode of a true electric vehicle using power of the motor 20; a hybrid electric vehicle (HEV) mode using torque of the motor 20 as auxiliary power while using torque of the engine 10 as main power; and a regenerative braking (RB) mode collecting braking and inertia energy through power generation of the motor 20 to charge the battery 60 during braking or driving using the inertia of the vehicle. In particular, the hybrid vehicle controls and/or manages the charge and discharge of the battery.
The corresponding exemplary embodiment of the related art discloses features of enhancing fuel efficiency by variably enlarging a reference region in which charge and discharge of a battery is performed during a cruise control state. Another exemplary embodiment of the related art discloses features of managing a battery for a hybrid vehicle based on a road state, for example, differently setting a charge range to determine charging/discharging according to driving on a flat road, an up-slope road, and a down-slope road.
However, the described exemplary embodiments of the related art have the following drawbacks and problems.
1. The described related arts are not methods associated with a charge power to substantially influence improvement of fuel efficiency, but are methods only limiting the number of battery charges and discharges by variably controlling a range of a state of charge (SOC) of a battery.
2. The described related arts are only applied to methods related to a cruise control state or a road state (e.g., a flat road, an up-slope road, a down-slope road, etc.).
3. The described related arts need a device to determine a running state and a road state.
4. The described related arts need a complicated logic to process substantial amounts of data received from associated controllers.
The above information disclosed in this section is merely for enhancement of understanding of the general background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.